Layout and Construction of Processing Plant

 

 Layout and Construction of Processing Plant

1. Typical Layouts

• Planning Stage: Focus on hygiene and economy.
• Compromise: Balance between conflicting requirements based on local conditions.
• Factory Layout: Depends on building size and shape.

Key Considerations for Factory Layout:

1. Separation of Materials:
• Keep raw materials and finished products apart to avoid cross-contamination.
• Maintain separation between cleaning and processing areas.
2. Drainage:
• Ensure drainage flows away from clean areas.
3. Wet and Dry Areas:
• Separate "wet" areas (washing, processing) from "dry" areas (weighing, packing).
4. Equipment Access:
• Design layout for easy access to equipment for cleaning and maintenance.
5. Refrigeration:
• Position refrigeration equipment in a common plant room.
6. Delivery and Dispatch:
• Keep raw material and finished goods delivery separate to prevent contamination.

2. Building

1. General

• New Construction or Alterations: Must comply with local building regulations.
• Hygiene and Efficiency: Aim for higher hygiene standards and economical space use.
• Fish Handling: Preferably on the ground floor for better drainage and accessibility.

2. Walls

• Material: Use smooth, waterproof materials like dense concrete blocks.
• Protection: Exposed steelwork should be protected against corrosion.
• Finish: Ceramic tiles are ideal; keep walls free of projections.
• Paints: Use light colors and suitable paints for wet conditions.

3. Floors

• Requirements:
• Hardwearing, nonporous, washable, well-drained, nonslip.
• Resistant to brine, ammonia, fish oils, and offal.
• Materials:
• Clay tiles (50 mm thick) are recommended.
• Avoid rubber and PVC due to susceptibility to fish oils.
• Asphalt is suitable for low-traffic areas.
• Drainage:
• A slope of 1:100 is ideal; avoid stagnant pools.
• Ensure watertight junctions between floors and walls.

Additional Notes

• Flooring Strategy: Use hardwearing tiles in high-wear areas and granolithic concrete elsewhere.
• Safety: Ensure slopes are manageable to prevent accidents; avoid areas where liquids can pool.

By following these guidelines, the layout and construction of a processing plant can be optimized for efficiency, hygiene, and safety.

Construction and Design Considerations for Fish Processing Facilities

1. Ceilings

• Surface Requirements: Ceilings should be smooth, continuous, and easy to clean.
• Material Considerations:
• Avoid moisture-affected materials; asbestos boards are unsuitable.
• Insulation is necessary to prevent condensation in cold weather.
• Ventilation:
• Ensure the roof space is well-ventilated.
• Consider forced warm air ventilation in extreme cases.
• Height Requirements:
• Clear internal height must accommodate production and storage needs.
• Allow for installation, removal, and maintenance of equipment.
• Ancillary equipment may require additional height.

2. Doors and Windows

• Material Selection: Use non-porous, non-absorbent materials; avoid wood.
• Design Features:
• Doors should have a flush surface for easy cleaning.
• Self-closing doors with kicking plates at the bottom.
• Window Frames:
• Use suitable aluminum alloys or heavily galvanized steel.
• Regular maintenance is required to prevent corrosion.
• Fly Proofing:
• Install fly proof screens during summer; self-closing doors are preferred.

3. Lighting

• Importance of Good Lighting:
• Essential for worker efficiency and cleanliness.
• Natural Light:
• Maximize natural daylight with windows and skylights.
• Artificial Lighting:
• Use fluorescent lights for diffused general lighting.
• Aim for a light level of 500-750 lux depending on tasks.
• Special Lighting:
• Augment general lighting with individual lights at inspection points.

4. Ventilation

• Humidity Control:
• Good ventilation reduces condensation and removes bacteria-laden air.
• Temperature Management:
• Maintain comfortable working conditions without spoiling products.
• Ventilation Methods:
• Use windows, skylights, exhaust fans, or roof vents.
• Duct Design:
• Fit ducts within walls or ceilings for easy cleaning.
• Ensure inlets are insect-proof and away from dust.

5. Drains

• Drainage Design:
• Floor drainage channels should have removable gratings.
• Main drains must have an intermediate trap before connecting to sewers.

6. Power Supply

• Future-Proofing:
• Plan for current and future electricity needs.
• Install ample capacity wiring and power points.
• Safety Compliance:
• Ensure all power points are earthed and waterproof as necessary.

7. Water Supply

• Accessibility:
• Provide a generous water supply at multiple points for processing and cleaning.
• Hand Wash Basins:
• Place near work areas for easy access.

8. Factory Yards

• Surface and Drainage:
• Ensure the yard has an even, impervious surface and proper drainage.
• Storage Requirements:
• Store returnable fish boxes in a clean, dry area.
• Offal bins should be deep-lidded and stored in outbuildings.

9. Site Selection

1. Factors to Consider:
• Cost of land and site preparation.
• Proximity to raw material supplies and markets.
• Local objections and conditions affecting building costs.
• Availability of water and power supplies.
• Ancillary support services like ice plants.
• Future expansion possibilities.
2. Site Level:
• A flat, level site is preferable for construction.

Insulation Materials and Refrigeration Systems

Insulation Materials

Expanded Perlite

• Application:
• Commonly poured and spread manually.
• Fills small spaces more completely than fibrous materials.
• Usage:
• Can be combined with other insulation types for irregular areas.
• Caution:
• Handling can cause chronic poisoning.

Fiberglass

• Properties:
• High resistance to fire, heat, and microbiological attack.
• Good chemical resistance with low thermal conductivity.
• Forms:
• Available in rolls (blankets) and mats of different thicknesses.
• Limitations:
• Poor structural strength and compression resistance.
• Tendency to settle if not installed properly.
• Permeable to moisture.

Usage of Ante-room

• Purpose:
• Slows spoilage of fish by lowering temperature.
• Freezing:
• Proper freezing and low temperatures can stop spoilage.
• Storage:
• Some deterioration occurs, but under optimal conditions, thawed fish can appear fresh.
• Key Factor:
• Lower storage temperature extends safe keeping period.

Refrigeration Systems

Thermodynamic Refrigeration Cycle

• Function:
• Removes heat from low-temperature objects and rejects it at higher temperatures.
• Process:
• Operates in a cycle returning the working substance to the same state.

Vapour Compression Refrigeration System (VCRS)

• Advantages:
• Efficient heat removal.
• Widely used in various applications.
• Disadvantages:
• Requires maintenance.
• Can be less efficient under certain conditions.

Theoretical vs Actual Cycle

1. Theoretical Cycle:
• Ideal conditions without losses.
2. Actual Cycle:
• Deviates due to:
• Pressure drops from friction in piping and valves.
• Heat loss or gain based on temperature differences.
• Polytropic compression due to friction and heat transfer.

Key Processes in Actual VCR Cycle

• Pressure Drops:
• Occur in various stages (evaporator, compressor discharge, etc.).
• Superheating:
• Occurs in the evaporator.
• De-superheating and Subcooling:
• Happens in the condenser.

Diagrams

• P-H and T-S Diagrams:
• Used to visualize the cycle and understand refrigerant behavior.
• Important for determining the Coefficient of Performance (COP) of the cycle.

Observations

• Pressure drop in the evaporator is generally larger than in the condenser due to frictional and momentum pressure drops.

Cold Storage and Insulation Materials

Site Preparation

• Cold Store Floor Level:
• Should be raised to about 1.4-1.5 , m for vehicle loading.
• Important in areas prone to flooding to keep the cold store above maximum flood levels.
• Natural Air Ventilation:
• Elevating the cold store helps prevent "frost heave."

Site Considerations

• Communications:
• Essential for the movement of goods and labor services.
• Site Size:
• Adequate space for vehicle access and maneuvering is crucial.
• Consideration for future expansion is important.
• Modular Construction:
• Allows for easy expansion by adding standardized units.
• Parking Space:
• Sufficient space for vehicles and equipment to avoid interference with operations.

Insulation Materials

Hair Felt

• Made from cleaned and compressed animal hair.
• Excellent insulator for refrigeration systems.

Cork Board

• Derived from the bark of oak trees.
• Properties:
• Light, porous, compressible, water-resistant, and insulating against heat and electricity.
• Uses:
• Lining for cold storage, bottle stoppers, packing gaskets.

Kopak

• Made from silken fibers of the corba tree root.
• Lightweight and used for domestic refrigerator insulation.

Celotex

• Made from the leftover material after sugar cane juice extraction.
• Properties:
• Lightweight, waterproof, and odorless.

Thermal Insulation Materials

• Selection Criteria:
• Initial cost, effectiveness, durability, and adaptability.
• Economic Consideration:
• Choosing materials with lower thermal conductivity may be more cost-effective than increasing thickness.

Polyurethane Foam (PUF)

• Excellent insulation for fishing vessels.
• Properties:
• Good insulating properties, low moisture permeability, high water resistance, and low density.
• Applications:
• Chill rooms, ice stores, and cold stores.
• Installation:
• Available as rigid boards/slabs and preformed pipes.

Expanded Polystyrene (Thermocol)

• Made from polymerized styrene into white beads, then expanded.
• Methods:
• Extrusion and molding.
• Limitations:
• Flammable, breaks down in sunlight, and reacts with solvents.

Expanded Perlite

• A volcanic rock that expands when heated.
• Properties:
• Good insulating efficiency when dry.
• Absorbs moisture, which can reduce effectiveness over time.

Summary

Choosing the right site and insulation materials is crucial for effective cold storage. Considerations include site elevation, communication access, space for vehicles, and the properties of insulation materials to ensure durability and efficiency.